1. Field of the Invention
The invention is mainly directed toward enabling all persons but especially pearl dealers jewelers and gemologists to surely identify natural pearls and distinguish them from cultured pearls of lesser value. The jewelry industry's standard manual for identifications declares this uncertainty about pearls to be the most difficult distinction, even for gem experts and for lack of any alternative, requiring X-ray examination by special laboratories. Such reference may be inconvenient or impossible in many business situations.
The invention thus arrives against a background of widespread general confusion even among experts, that has endured all of the approximately 100 years since advent of cultured pearls looking somewhat like those natural ones treasured throughout the world for millennia. The Bible mentions pearls ten times, diamonds only three. The United States has imported in a year as much as 500 million dollars worth of cultured pearls and cultured pearl jewelry. Most such pearls may consist more than 90 percent of mother-of-pearl bead nucleus made from Mississippi or Tennessee river clamshell costing about 30 cents per pound.
The clamshell beads were found to be compatible material which when surgically inserted into the oyster, caused fewer mortalities of the host mollusks. In three years the added layers of nacre (calcium carbonate) add at most one-half millimeter of overcoat, equal to half the thickness of a paper match stick. Many cultured pearls have even less nacre. With the invention, the mostly straight lines of the bead inside become sharply visible, looking like the edge of a sandwich or a layer cake, a firm answer to identity. Most jewelers are aware in a general way of the cultured pearls pretense but find it profitable. Few of today's American customers have any acquaintance with real pearls. Most have never owned any.
Chiefly from estates there are still in private hands many real pearls, singly or in necklaces and these may confront the trader with decisions between a few hundred dollars and thousands. He may know his diamonds and rubies but be blind in pearls or be aware his expertise is limited.
2. Description of the Prior Art
In the past there have been many efforts and devices to separate natural and cultured pearls at a laboratory level. None was practical, convenient and certain.
One required a hole be drilled through the pearl. Then a tiny mirror and light were inserted and there might be seen the circular lines of added nacre. Another method was to measure the specific gravity against the known number for natural pearl, etc. It is sometimes suggested that a way to identify cultured pearls in a necklace is to hold the necklace in a straight line on white paper beneath a lamp then rotate the pearls to observe whether they show a flash when the covered mother-of-pearl beads reach an aspect reflecting light. Flashing would be from the bright plane of mother-of-pearl occurring twice in 360 degrees. Inasmuch as the beads are drilled at random, such coincidence is chancy. This technique offers nothing to verify natural pearls. All these and other attempts fell short of anything for widespread use.
The most effective method and still the general last resort, has been X-ray and that only in a few special laboratories, not your neighborhood dentist. X-ray has offered views of many natural pearl's internal structures and may also reveal diagnostic fluorescence.
Candling viewing pearls of any kind by placing a light behind them, has been mentioned repeatedly but always with disdain. Candling or backlighting to see the interior, has long been familiar for the detection of hens eggs with an embryo, to cull these from food marketing. But until the invention, no pearl-identifying apparatus has used transmitted light and been practical and dependable. There are patents for identification and evaluations of gemstones. These variously rely upon the degrees of bending light, computer digitalizing of colors, etc. and all relate to mineral gems, not organics such as pearls. The pearl is the only gem that neither needs nor will tolerate without harm embellishment by man. This doubtless has postponed its technical conquest.